Embodiments of the present invention relate generally to gas turbines and, more particularly, to predicting and managing gas turbine component life.
Gas turbines are widely used to generate mechanical work for power plants, liquefied natural gas (LNG) plants, and other industrial applications. In such applications, the gas turbine operates as a prime mover, where a fuel (such as natural gas) is burned to produce power. During operation, gas turbine parts are exposed to extremely hot and harsh conditions. For example, gas temperatures in a turbine section routinely cause oxidation and deformation (commonly known as creep) of both rotating and stationary components in the turbine section. Moreover, the rotating parts of the turbine section must continuously withstand large centrifugal loads, while being subjected to thermal stresses. Such high temperatures, centrifugal loads, and thermal stresses may lead to various failure modes of the gas turbine such as fatigue (causing crack initiation and propagation), oxidation (forming of metal oxides which degrade the structural integrity of the gas turbine parts), thermal barrier coating spallation, and creep (permanent plastic deformation which can lead to cracking, dimensional changes, or rubs between static and rotating hardware). Such failure modes may lead to degraded power output, or in more severe instances, liberation of internal parts, which in turn can lead to unplanned outages and equipment damage.
Therefore, gas turbines are typically inspected at predefined intervals of time to identify any damage that the gas turbine components may have sustained. For some types of component inspections, the gas turbines are required to be shut down. This may result in revenue losses and undesirable downtime, especially when such inspections are performed during high power demand periods. Moreover, it may be desirable in some cases to operate the gas turbine at higher capacity than nominal, to generate higher revenues. However, such operations need to be performed carefully and without undue impact on downtime.
It would be desirable to have an improved operating method and maintenance scheduling system which can allow for adjustments in the operation of a turbine.